Automotive seats usually include a seat bottom that is affixed to a seat frame. The seat frame is mounted to the floor of the vehicle via a rail-type adjustment system to allow the forward and rearward adjustment of the seat bottom. The seat back is attached to the seat frame by a seat back support. If the seat is a reclining-type seat where the seat back is rotationally movable with respect to the seat bottom, a locking and release mechanism is usually provided. The seat reclining mechanism usually includes a base that is affixed to the structure of the seat frame. The seat back support is pivotally mounted to such base as it is desirable to have the seat back move forward and rearward with the seat bottom. The locking and release mechanism by which the seat back is held in a fixed angular position relative to the seat bottom has several known forms. One form is a ratchet mechanism where a notched wheel is affixed to either the seat back or seat bottom and a pawl is attached to the other. Upon the pawl disengaging the notched wheel, the seat back is released and is free to rotate at its pivot with respect to the seat bottom. Other types of engaging or intermeshing gear-type mechanisms provide a locking and a releasing operation between the seat bottom and seat back.
In manual reclining seat back adjustments, the reclining seat backs may be physically adjusted by the occupant of the seat by releasing a latching or locking mechanism and simply leaning back to displace the seat back to a desired position, at which time the latch or lock is re-engaged. Usually biasing spring means are provided, effective to adjust the seat back forwardly when unlocked and such movement is unopposed by the occupant.
A reclining seat back which is power operated is adjustable both forwardly and rearwardly. The power source typically is a reversible electric motor, which drives the seat back through a train of gears contained in a transmission housing fixed to a seat mount or bracket. In many cases, the gear train can require a large transmission housing, and may also require that a complementary gear train be positioned on an opposite side of the seat back with an interconnecting drive mechanism between the two gear trains, the extra weight of this dual recliner system negates the weight saving which it makes possible in the structure of the seat back frame.
Therefore, it is desirable in the present invention to provide a compact gear train which requires a small amount of space. It is also desirable in the present invention to provide a gear train which exhibits an increased load carrying capacity without a weight penalty that allows the mechanism to be profitably used as both a single or a dual sided recliner. Furthermore, it is desirable in the present invention to provide a gear train with a load carrying capacity capable of eliminating the need for dual transmission housings on either side of a single passenger recliner seat, thereby eliminating the additional space requirements and weight of the duplicate transmission housing and interconnecting actuator mechanism.
Certain drawbacks are also present in the known seat back locking and release mechanisms. Due to the potentially great forces to which a vehicle seat back can be subjected, a locking mechanism at the pivot between the seat back and seat bottom has been a relatively large and heavy unit. This is undesirable in the ongoing attempt at decreasing the weight of vehicles to achieve greater fuel efficiency.
One other problem with such known seat back support locking mechanisms is that a finite number of reclined positions are possible depending on the number of notches in the ratchet wheel. It is not desirable to make the notches very small and closely spaced to provide many possible reclining positions, because of the strength required of the locking mechanism. Rather, the number of reclining positions is limited because of the need to have quite strong notches and protrusions from the ratchet wheel.
A locking mechanism having an infinite number of settings is therefore desirable in the present invention. Further, it is desirable in the present invention to provide extra torque capability with no increase in size of the gear train. In addition, it is desirable in the present invention to provide high shock resistance, and the ability to withstand heavy starting and stopping loads. It is also desirable in the present invention to eliminate backlash in the gear train to greatly reduce or eliminate any undesirable noise or more importantly seat back movement otherwise known as "chuck" that may be caused by forces acting on the seat back especially when the seat is occupied. It is further desirable in the present invention to provide increased durability.